CO2
and Beautiful Aquatic Plants

To successfully grow beautiful plants, all the plants' needs must be
met. Plants require proper nutrients, all of which can be met with regular
use of Yamato Green. Adequate light must be provided, generally defined
as fluorescent tubes not over 8 months old, with a total of about 2-4
watts per gallon of water. The often overlooked secret to success is
supplemental Carbon Dioxide, or CO2. Plants require sufficient quantities
of Carbon to build their leaf structure. Some plants can extract this
carbon from the water by splitting the carbonate component of calcium
carbonate in water, a process known as Biogenic Decalcification. However,
many plants (Cabomba, for example) are incapable of biogenic decalcification,
and cannot reach their full potential without a supplemental source of
carbon. Also, biogenic decalcification can cause a dramatic increase
in pH, up to pH 9 or so - not very conducive to good plant growth!! Meeting
the carbon needs of aquatic plants is best achieved by adding CO2 to
the water. The common methods are to use CO2 tanks, and Do-It-Yourself
(DIY) carbon dioxide generators. Certainly CO2 tanks are more convenient,
and eliminate the need to service the system every 2 or 3 weeks, as required
by a DIY carbon dioxide generator. Still, a good CO2 system can easily
cost $300 and up. And what if you have 2, 3, 4 or more tanks? The expense
can quickly mount up. DIY CO2 generators are nothing if not dirt cheap.
They can be constructed for less than a dollar, and they do work beautifully.
CO2 is generated in liberal quantities by the action of ordinary yeast
on sugar. By providing a closed container for this reaction, the CO2
generated can be routed into the aquarium.

CO2 Injection Results

With supplemental CO2, you will suddenly discover that growing
difficult plants becomes easy. CO2 is vital for red plants such as Ludwigia,
Rotala or some species of Cabomba. Some of these plants will grow without
extra CO2, but will not develop their beautiful red coloration. Once
you add CO2 to your tank, you will never go back. Plants you once thought
you could never grow suddenly become easy. One caution: keep track of
your KH (Carbonate Hardness) readings of your water, since CO2 forms
a weak acid (Carbonic Acid) that can slowly reduce your KH levels in
your water. If KH is allowed to reach zero, pH can drop precipitously.
If your KH reads less than 4, try adding a little Sodium Bicarbonate
(Baking Soda) to increase KH. Regular water changes become vitally important
in tanks with supplemental CO2, since water changes will constantly replenish
the water's natural buffers, helping to maintain a more steady pH.

Building a DIY Yeast/Sugar CO2 generator

CO2 can be generated
in a closed system (also called a juice bottle). The gas is then
fed via a length of airline tubing to the aquarium, where it can
be fed into a CO2 reactor, or it can be directed into the intake
screen of an ordinary Hang On Back (HOB) power filter. Since the
reaction generates a lot of pressure, the ideal reactor is made
of glass or metal. However, glass bottles are becoming scarce as
more and more manufacturers of beverages switch to cheaper, lighter
weight plastic containers. Fortunately, these plastic containers
can be used. Lightweight soda pop bottles are not desirable because
they can collapse very easily, and the contents of the CO2 generator
can accidentally wind up in your aquarium. The stronger bottles
as used for Gatorade, Welch's Grape Juice or similar make ideal
CO2 generators. The 2-quart (or 2 Liter) bottles are perfect. To
make a generator, drill a small hole (3/16") in the middle
of the cap of the bottle. Then, insert an airline tubing connector,
the kind that come with disposable plastic airstones, in the hole.
An airtight seal is imperative, or gas will leak and never make
it into the aquarium. Ordinary Goop Household Adhesive & Sealant
is the only glue readily available that will stick to the plastic
bottle cap of a beverage container, and should be used under and
around the plastic connector as it is inserted in the hole. Allow
the glue to dry 24-72 hours, to allow all the volatile gases from
the glue to disperse. The next day, add 2 cups of sugar and 1/2
teaspoon of ordinary baker's yeast to the container. If you live
in a soft-water area (i.e., your water has a naturally low pH),
you may wish to add 1/2 tsp baking soda to assist the mixture to
produce CO2. Baking soda is not necessary if you live in a moderate
or hard water area. Then, fill the container about 3/4 full of
warm (not hot) water, and shake. Replace the prepared bottle cap,
and secure a 6'-8' length of airline tubing to the plastic fitting
on top of the bottle cap. (Special silicone tubing resistant to
CO2 can be used in place of ordinary airline tubing.) For safety's
sake, use a one-way check valve, to prevent back-flow of water
into the generator bottle. Do NOT attempt to control rate of gas
flow by inserting a valve! If you restrict the flow of gas, you
may end up with a ruptured yeast/sugar bottle, and quite a mess
on your floor! Nothing should ever restrict the flow of gas from
a yeast/sugar bottle. Route this tubing into the aquarium, either
to a commercial CO2 reactor (Aqualine Buschke, Eheim,
etc.), or into the inlet screen of a power filter (such as the
AquaClear, or into the inlet screen of a canister filter such as
the Eheim. (Fluval canister filters probably are not as desirable
for CO2 dispersal, since they have been reported to have some problems
accepting CO2 in their intakes.) Secure the end of the tubing with
rubber bands or plastic ties to hold the end of the airline tubing
close to the inlet screen. CO2 gas will be sucked into the filter,
where it will strike the impeller blades and be shattered into
jillions of microscopic bubbles. These bubbles will be absorbed
into the water within seconds. The desirable CO2 level for plants
is around 10-20 mg/L. The actual amount of CO2 you have in your
water can be calculated quickly with a pocket calculator, using
the formula: CO2 = 3 x KH x 10^(7-pH). This formula is also sometimes
expressed as: CO2 = KH x 10^(7.5-pH). For your convenience, ahandy
CO2 Chart to quickly look up your CO2 levels is posted on
Uniquaria by Giancarlo Podio. Do not allow CO2 levels to exceed
40 ppm, or they may become harmful to fish. The DIY CO2 generator
will ordinarily last for 2-3 weeks before requiring a fresh load
of sugar/yeast/water.